Stay-bolt and process of making same.



No. 699,678. Patented May 13, 1902.

G. 0. G'RIDLEY;

STAY BOLT AND PROCESS OF MAKING SAME.

(Application filed May 24, 1900.)

(No Model.)

lTED STATES Arena ()FFICE.

GEORGE O. GRIDLEY, OF WINDSOR, VERMONT.

STAY-BOLT AND PROCESSOF MAKING SAME.

$PECIFJEGATION forming part of Letters Patent No. 699,678, dated May 13,1902. Application filed May 24, 1900. Serial No. 17,807. (No model.)

To (tZZ whom it may concern.-

Be it known that LGEORGE O. GRIDLEY, of IVindsor, in the county of\Vindsor and State of Vermont, have invented certain new and usefulImprovements in Stay-Bolts and Processes of Making Same, of which thefollowing is a specification.

This invention has relation to stay-bolts for boilers and to processesfor making the same, the main object of the invention being theproduction of a stay-bolt having provisions for accurate insertion inthe walls or sheets of the boiler.

Another object of the invention is the provision of a stay-bolt soformed or constructed as to be more durable and less liable to fractureor cracking when used in boilers than as heretofore constructed.

. Other objects of the invention are to provide certain improvements instay-bolts and in processes for making the same, whereby the stay-boltsmay be constructed more easily and cheaply than hitherto and may beprovided with certain improvements which render them easier of insertionin the boilersheets and capable of indicating their condition. v

Up to the present time it has been the practice to tap the adjacentsheets of the boiler by means of a single tap, whereby the internalthreads of the sheets are practically continuous of each other; but sofar as I am aware no provision has yet been made foraccurately threadingthe bolt to fit in the apertures, since it has been the custom toseparately cut the threads on the ends of the bolt. This cutting of thethreads not only prevents the accurate location of the threads withrelation to each other to render them continuous in all cases, butprovides interstices transverse of the axial line of the bolt, which areliable to extend still farther into the body of the bolt and eventuallyseparate the ends. According to myinvention, however, I thread the twoends of the bolt simultaneously by means which do not out into the bodyof the bolt, but compress or compact the outer surface into a tough anddurable skin. This is accomplished in my invention by rolling thethreads on the bolt between corrugated or threaded plates, whereby inthe resulting or finished bolt the threads at both ends are of the samelead or pitch and are continuous of each other, so that when the bolt isscrewed into the sheets of the boiler the threads on the ends of thebolt accurately register with the internal threads in both theboiler-sheets. By this formation of the bolt I materially reduce theliability of the bolt to crack at its juncture with or at a point nearthe boilersheet, the outer skin being so compacted or compressed as tobe tough, and thus lesson the dangerof fracture. Consequently the escapeof steam or the leakage of water from the boiler is more effectuallyprevented than has hitherto been possible with stay-bolts as ordinarilymade, for it will be readily seen that whereas in previous constructionsthe formation of threads by a cutting operation left an incipient crackor fracture at the base of each thread, which soon opened and permittedthe leakage of water andsteam, the rollingof the threads to form a toughand compacted skin renders the stay-bolt strong and unliable to crackand permit such leakage.

Iprefer in many cases to first upset the ends of the boltprior to therollingand threading operation in order that the middle portion of thebolt may be of less diameter than the ends, for the bolt is therebyrendered more elastic or resilient, less expensive in construction, andthe labor of threading the whole length of the bolt is saved.

I regard it as desirable to form in each end of the bolt a longitudinalaperture, which extends into the middle portion thereof, so that in casethe bolt cracks there will be a duct for the escape of steam or waterfor indicating to the engineer or individual employed about the boilerthe condition of the bolt. This aperture may be formed simultaneouslywith the operation of upsetting the ends of the bolt, and I prefer to soform it, because it saves the separate heating of the bolt and aseparate operation. The punching of the aperture is preferable todrilling a hole in the end, as the former is easily done, since theinternal wall of the aperture is made tougher and more durable and thereis less liability to crack than where the hole is drilled, for the drillseems to leave the shoulders or grooves from which the cracks are apt tostart.

In order to provide for driving the belts in the apertures in theboiler-sheets, provision must be made for receiving the wrench or othertool, and hence in forming the said bolt I either square the aperturewhich extends into the end or else square the end of the bolt, wherebyin either case the wrench may be engaged with the tool fol-turning it.

Referring to the drawings which accompany this specification, Figure 1represents a cylindrical bar of metal from which the staybolt is made.Fig. 2 illustrates a step in the process of manufacturing the stay-bolt,the latter being shown as having its ends upset and a punch driven insaid ends to form an angular hole therein. Fig. 3 illustrates one ofthethreading members or plates. Fig. 4E represents a finished stay-boltwith one end in section. Fig. 5 represents the operation of forming thethread simultaneously on the two ends of the stay-bolt.

Referring to said drawings, I first form a cylindrical blank to, asshown in Fig. 1, of suitable length and of a cross-diametersubstantially equal to the diameter of the central portion of thefinished bolt. The blank is then placed in a suitable holder, (notshown,) and the ends are upset.

Z) l) in Fig. 2 represent oppositely-moving dies which engage the endsof the blank and compress the metal to cause it to swell at the ends-andproperly [it in the holder. The dies carry the punches c c, which aresquare in cross-section and have tapering points 0 to projectwell intothe body of the stay-bolt. The action of the dies and punches is to forma blank having the ends ct of relatively large diameter, the bodyportion a of less diameter, and the shoulder a at the juncture of theends and the said central portion. The punches 0 form in the ends of theblank apertures a which are larger at their mouths and contract as theyextend longitudinally into the blank. A square aperture is thus providedat each end of the stay-bolt for the reception of a square tool, bymeans of which the finished bolt may be screwed home in the sheets ofthe boiler. It is not essential that the aperture may be squared at bothends, and, in fact, I square it in practice at only one end.

After the blank has been upset at the ends and the apertures have beenpunched therein it is ready for the threading operation. To perform thisoperation,I provide two plates or threading members cl d, which arearranged in parallelism, one of said plates being movable in its planewith respect to the other. The two opposing surfaces of the two membersare provided with a plurality of parallel V-shaped grooves and A-shapedteeth, which are slightly inclined with respect to the squared ends ofthe plates to correspond to the pitch or lead of the threads'to beformed on the ends of the stay-bolts. These members are wide enough tocover both ends of the stay-bolt, and the grooves or corrugations in thefaces of the said members are continuous from edge to edge.

Byplaeing the blank between the two members, in which the grooves areexactly similar and of precisely the sameinclination, one of the platesor members is moved'transversely of the axis of the stay-bolt, and thestay-bolt is therefore rolled along the surface of the other plate ormember. This rolling operation causes the formation of threads upon theupset ends of the stay-bolt, the said threads being exact continuationsof each other by reason of the grooves and teeth being continuous in thethreaded members from edge to edge thereof.

The rolling of the threads is the most important feature of myinvention, for I thereby not only accomplish the formation of threads atthe two ends of the bolt which are continuations of each other, but Ialso compact or compress the outer surface at the end of the boltso asto form a tough and durable skin, as previously stated, and, so far as Iam aware, I am the first to have manufactured or formed a stay-bolt inthis way.

I do not limit myself to the employment of any particular mechanism foraccomplishing the various steps in the process whichI have described forthe manufacture of the bolt, for any machines or tools maybe used whichwill accomplish the several results set forth.

By the provision of the elongated central apertures c, which extend intothe body of the stay-bolt between the threaded ends, provision is madefor the escape of water in case the said bolt should by imperfection inthe stock become cracked or otherwise defective, so that the engineer orfireman may be made aware of such crack or defect.

Having thus explained the nature of the invention and described a way ofconstructing and using the same, although without attempting to setforth all of the forms in which it may be made or allof the modes of itsuse, I declare that What I claim isl. The herein-described method ofmaking a stay-bolt for boilers which consists in simultaneously rollingthe threads at both ends of the said stay-bolt and thereby making saidthreads continuous of each other and forming on the said bolt a surfaceor skin which is compacted or compressed.

2. The herein-described method of making a stay-bolt for boilers whichconsists in upsetting the ends of a cylindrical blank, andsimultaneously rolling the threads on the said upset ends, whereby saidthreads are continnations of each other.

3. The herein-described method of making a stay-bolt for boilers, whichconsists in simultaneously upsetting and preparing an end of a suitableblank for a tool for turning it, and then threading the said upset ends.

4:. The herein-described method of making stay-bolts for boilers, whichconsists in providing a cylindrical blank, upsetting the ends thereof,and simultaneously rolling threads on the two ends of thepartially-formed staybolt, whereby the threads thereon are practicallycontinuations of each other, and the surface or skin of the threadedpart is com-- pacted or compressed.

5. The herein-described method of making stay-bolts for boilers,consisting in providing a suitable cylindrical blank, simultaneouslyupsetting an end and punching a hole in the said end of the said blank,and then rolling threads on the upset ends.

6. As a new article of manufacture, a staybolt for boilers havingthreads rolled on its ends whereby the surface of said ends iscompressed or compacted, the threads on one end being 'continuations ofthe threads on the other end.

7. As a new article of manufacture, a stayholt for boilers having upsetends, and threads simultaneously rolled on said ends, whereby the saidsurfaces of the said ends are comwith threads which are rolled thereonandwhich are in effect continuous.

In testimony whereof I have aflixed my signature in presence of twoWitnesses.

GEORGE O. GRIDLEY.

Witnesses:

W. 0. TUXBURY, F. M. SMITH.

